Apparatus and method for testing jet engine fuel manifold flow distribution

ABSTRACT

An apparatus and method for testing the flow distribution through a turbine engine fuel manifold and one or more nozzles connected to the manifold. A plurality of individual fluid measurement vessels, at least one for each of the nozzles being tested, collects test fluid pumped through the manifold and the connected nozzles. The level in each of the measurement vessels is periodically sampled during the test. The test fluid flow rate through each of the nozzles is periodically determined based on the periodically sampled levels.

RELATED APPLICATIONS

This is a divisional of and claims priority from application Ser. No.09/960,897 entitled “Apparatus and Method For Testing Jet Engine FuelManifold Flow Distribution”, filed Sep. 21, 2001, now U.S. Pat. No.6,672,145 which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method for testing jetengine fuel manifolds and, more particularly, to an apparatus and methodfor testing the flow distribution in jet engine fuel manifolds.

Modern jet aircraft use turbofan jet engines to generate the thrust thatmoves the aircraft on the ground and through the air. One of the majorcomponents of the turbofan engine is the combustor. The combustorreceives compressed air from the compression portion of the engine,mixes the air with fuel supplied from fuel injector nozzles, and ignitesthe fuel/air mixture in a combustion chamber, thereby significantlyincreasing the energy of the air flowing through the engine. Thehigh-energy air exiting the combustor expands through a turbine, whichdrives the compressor, and through a nozzle, to provide thrust.

The fuel injector nozzles that supply the fuel to the combustion chamberare coupled to a manifold that is located circumferentially around theengine. If fuel flow through the injector nozzles is uneven, for exampleif fuel flow through one or more of the fuel injector nozzles issignificantly higher than other nozzles, large temperature variations inthe hot gas that exits the combustor and impinges upon the turbine willresult. These large temperature variations cause unwanted stresses inthe turbine, which leads to early replacement of costly turbinecomponents, including the combustors, transition liners, and turbinenozzles.

Uneven fuel flow through the injector nozzles is caused by variousdefects. For example, if a portion of the manifold, or one or more ofthe injector nozzles, becomes clogged, then fuel flow through theremaining injector nozzles will be higher than the others. Additionally,after usage one or more of the injector nozzles may wear, resulting in alarger nozzle opening than the other injector nozzles coupled to themanifold.

In order to check for uneven fuel manifold flow distribution, the fuelinjector manifolds are periodically removed from the engines and subjectto flow distribution testing. Presently, this testing is conducted usingone of two known test devices. One of these test devices consists of atest stand that includes one measurement vessel for each injectornozzle. To conduct the test, the fuel manifold and injector nozzles areremoved from the engine and are connected to the test stand. A testfluid is then pumped into the manifold and through the injector nozzles,and a predetermined minimum volume of test fluid is collected in each ofthe individual measurement vessels. After the predetermined volume iscollected, test fluid flow is stopped and an operator observes how muchfluid is collected in each of the individual measurement vessels. Theoperator then compares the volumes accumulated from each nozzle andcalculates the flow distribution as [(max−min)/max]×100, to ensure thisis below the limit.

Another known test device also consists of a test stand that includes ameasurement vessel for each injector nozzle. However, each of themeasurement vessels has a pair of associated optical level sensors. Totest a fuel manifold with this device, the fuel manifold and injectornozzles are removed from the engine and are connected to the test stand.A test fluid is then pumped into the manifold and through the injectornozzles, and is collected in each of the individual measurement vessels.As the rising level in each vessel passes the lower optical sensor, ahigh frequency clock begins counting; as the level reaches the upperoptical sensor, the clock stops, and test fluid flow is stopped. Acomputer determines the flow rate through each of the nozzles based onthe time required to fill each vessel to a known volume.

Each of the above-described methods and apparatuses for testing fuelmanifold flow distribution has its disadvantages. The first test deviceand method exhibits a large measurement uncertainty (e.g., +/−2%repeatability), due in large part to the operator subjectivity in themeasurement and to the coarse graduations of the measuring vessels. Thislarge amount of uncertainty limits the ability of engine maintenance andtesting facilities to accurately determine when fuel distributionmanifolds are actually exhibiting uneven flow distribution. Although thesecond test device alleviates the operator subjectivity somewhat, itstill suffers numerous disadvantages. For example, the measurementvessels used with this device are opaque and, therefore, do not allow anoperator to view the spray pattern of the test fuel as it exits theinjector nozzles. In addition, the level sensors used in the device donot provide real-time level sensing and display throughout the test.Thus, an operator will not be able to clearly detect a fault in thesystem and abort the test, until after the predetermined time period haselapsed. In addition, the device is not configured as a closed loopsystem, which means that the test fluid pumped through the fuel manifoldand into the measurement vessels is not conveniently drained or pumpedback to the reservoir from where it originated.

Hence, there is a need for a fuel distribution manifold test device andmethod that improves upon one or more of the drawbacks identified above.Namely, a device and method that provides increased accuracy andrepeatability, and/or provides real-time level sensing and displaythroughout the test, and/or allows operators to view the fuel nozzlespray patterns during the test, and/or is provided in a closed loopsystem configuration.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus and method for testing theflow distribution through a turbine engine fuel manifold and one or morenozzles connected to the manifold. One embodiment of the presentinvention allows an operator to view individual measurement vessellevels, view real-time flow data through each of the nozzles, andsimultaneously view the fuel nozzle spray patterns throughout the test.

In one aspect of the present invention, an apparatus for testing fluidflow distribution through a turbine engine fuel manifold and one or morefuel nozzles connected thereto includes a test fluid supply tank, one ormore test fluid supply lines, a plurality of fluid measurement vessels,a plurality of level sensors, and a computer. The test fluid supplylines each include a test fluid inlet in fluid communication with thetest fluid supply tank and a test fluid outlet adapted to be coupled tothe fuel manifold and its connected fuel nozzles. The plurality of fluidmeasurement vessels are each operable to receive a test fluid dischargedfrom one of the fuel nozzles when the fuel manifold is coupled to thetest fluid supply line outlet. The plurality of level sensors areindividually coupled to each of the fluid measurement vessels and areoperable to determine a level of the test fluid therein and generate alevel signal representative of the test fluid level. The computer iscoupled to the one or more level sensors and is operable to periodicallysample each of the generated level signals and calculate test fluid flowrate through each of the fuel nozzles based on the sampled levelsignals.

In another aspect of the present invention, a method of testing fluidflow distribution through a turbine engine fuel manifold and one or morefuel nozzles connected thereto includes supplying a test fluid to thefuel manifold at a predetermined pressure, and collecting the test fluiddischarged from each of the fuel nozzles in separate measurementvessels. The volume of test fluid discharged from each of the fuelnozzles is periodically determined until each of the measurement vesselshave collected a predetermined volume of the test fluid. The test fluidflow rate through each of the fuel nozzles is periodically calculatedbased on the periodically determined test fluid discharge volume.

In yet another aspect of the present invention, a computer-readablestorage medium containing computer executable code for instructing acomputer, which is coupled to a test stand that is configured to testfluid flow distribution through a turbine engine fuel manifold and oneor more fuel nozzles, and that includes a plurality of fluid measurementvessels each operable to receive a test fluid discharged from one of thefuel nozzles, to perform the steps of periodically determining anddisplaying a volume of test fluid discharged from each of the fuelnozzles until each of the measurement vessels have collected apredetermined volume of the test fluid, and periodically calculating anddisplaying test fluid flow rate through each of the fuel nozzles basedon the periodically determined test fluid discharge volume.

Other independent features and advantages of the preferred sensor willbecome apparent from the following detailed description, taken inconjunction with the accompanying drawings which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic cross section view of a turbofan jetengine;

FIG. 2 is a perspective view of a jet engine fuel manifold that may beused in the turbofan jet engine depicted in FIG. 1;

FIG. 3 is a front view of a machine for testing fuel manifold flowdistribution according to an embodiment of the present invention;

FIG. 4 is a schematic representation of a test fluid supply unit whichforms a portion of the machine depicted in FIG. 3;

FIG. 5 is a schematic representation of a flow test unit which forms aportion of the machine depicted in FIG. 3;

FIG. 6 depicts a cross section side view of a single measurement vesseltaken along line 6—6 of FIG. 3;

FIG. 7 depicts a front view of a control unit which forms a portion ofthe machine depicted in FIG. 3;

FIG. 8 depicts a block diagram of the circuitry associated with each ofthe various sensors used in the machine depicted in FIG. 3;

FIG. 9 depicts a block diagram of the circuitry associated with each ofthe various pumps and control valves used in the machine depicted inFIG. 3;

FIG. 10 depicts a block diagram of the circuitry associated with variousremotely controlled throttle valves used in the machine depicted in FIG.3;

FIG. 11 illustrates an exemplary user interface screen display providedon a display device which forms a portion of the control unit depictedin FIG. 7;

FIGS. 12A and 12B depict a process for testing jet engine fuel manifoldflow distribution using the machine depicted in FIG. 3; and

FIG. 13. depicts an example of the content and format of a computerprintout providing the results of the testing processes depicted inFIGS. 12A and 12B.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A simplified schematic cross section view of a turbofan jet engine isdepicted in FIG. 1. As this figure illustrates, a turbofan jet engine100 consists of six major parts or sections. These major parts orsections are a turbofan 102, a bypass section 104, a compressor 106, acombustor 108, a turbine section 110, and an outlet nozzle 112.

The turbofan 102 is positioned at the front, or “inlet” section 101 ofthe engine 100, and induces air from the surrounding environment intothe engine 100. The turbofan 102 accelerates a fraction of this air intoand through the bypass section 104, and out the outlet nozzle 112. Theremaining fraction of air that is not directed through the bypasssection 104 is directed toward the compressor 106, which raises thepressure of the air to a relatively high level. This high-pressurecompressed air then enters the combustor 108, where a ring of fuelinjector nozzles 114 injects a steady stream of fuel. The injected fuelis ignited by a burner (not shown), which significantly increases theenergy of the high-pressure compressed air.

The high-energy compressed air then flows from the combustor 108 intothe turbine section 110, causing rotationally mounted turbine blades 111to turn and generate energy. The energy generated in the turbine section110 is used to power other portions of the engine 100, such as theturbofan 102 and compressor 106. The air exiting the turbine section 110then leaves the engine 100 via the outlet nozzle 112. The energyremaining in this exhaust air aids the thrust generated by the airflowing through the bypass section 104.

As was previously noted, the fuel injector nozzles 114 that supply thefuel to the combustor section are coupled to a manifold that is locatedradially about the engine 100. An exemplary embodiment of one such fuelmanifold 200 is illustrated in FIG. 2. The particular manifold assembly200 depicted in FIG. 2 consists of a matched set of manifoldsub-assemblies 202, 204, one for each side of the combustor 108. Eachmanifold assembly 202, 204 includes a plurality of flexible conduitsets, consisting of a primary conduit 206 and a secondary conduit 208,interconnecting the individual fuel injector nozzles 114 a-l.

The fuel injector nozzles 114 a-l are generally identical, in that eachincludes a body portion 115, and separate internal primary and secondaryflow paths (not depicted) that direct fuel through a nozzle portion 117.However, as can be seen in FIG. 2, the fuel injector nozzles 114 a-l arenot all identical externally. More particularly, while each of the fuelinjector nozzles 114 a-e and 114 g-k includes an inlet port 212 and anoutlet 214 for primary fuel flow, and an inlet port 216 and an outletport 218 for secondary fuel flow, end fuel injector nozzles 114 f and114 l includes only a primary 212 and a secondary 216 inlet port, and nooutlet ports. In addition, the other end fuel nozzles 114 a and 114 fare shaped differently from the remaining injector nozzles 114 b-e and114 h-k, in that its primary 212 and secondary 216 inlet ports arepositioned to conveniently couple the manifold sub-assemblies 202, 204to the aircraft's fuel distribution system (not shown).

During normal operation of the engine 100, when both primary andsecondary fuel flow (referred to as “combined flow”) is used, fuelenters the end fuel nozzle 114 a and 114 g via their primary 212 andsecondary 216 inlet ports. A portion of the fuel is ejected out thenozzle portion 117, and the remaining portion is directed out theprimary 214 and secondary 218 outlet ports. The primary and secondaryfuel flow is then coupled to the next nozzles 114 b, h via the primary206 and secondary 208 fluid conduits, respectively. The primary andsecondary fuel flow through the remainder of the fuel nozzles 114 b-eand 114 h-k is identical until it reaches the end fuel nozzles 114 f and114 g, which have no outlets other than their nozzle portion 117. Fuelflow through each of the manifold sub-assemblies 202, 204 is similarwhen only primary, or only secondary, fuel flow is used, except thatfuel does not flow in and through the non-used portions of the manifoldsub-assemblies 202, 204. In other words, if only primary fuel flow isbeing used, such as during engine start-up or idle operations, then fuelflows through only the primary flow path portions of the fuel nozzles114 a-l and manifold sub-assemblies 202, 204. Conversely, if onlysecondary fuel flow is being used, which is rare (if at all) duringnormal engine operations, then fuel flows through only the secondaryflow path portions of fuel nozzles 114 a-l and the manifoldsub-assemblies 202, 204.

The fuel manifold assembly 200, as was previously noted, is periodicallyremoved from the engine 100 and subject to flow distribution testing.This testing is accomplished by connecting the fuel manifoldsub-assemblies 202, 204 to a testing machine, and determining the flowdistribution through each of the fuel nozzles 114 a-l. One such machine,which is the subject of the present invention, is depicted in FIGS.3-11, and will now be discussed in detail.

Referring first to FIG. 3, a front view of a machine for testing fuelmanifold flow distribution, according to a preferred embodiment, isdepicted. The test machine 300 includes three main components, the testfluid supply unit 302, the flow test unit 304, and the control unit 306.In general, the test fluid supply unit 302 stores and supplies a testfluid to the flow test unit 304. The fuel manifold assembly 200 iscoupled to the flow test unit 304, and the test fluid supplied from thefluid test supply unit 302 flows into and through the manifold assembly200 and associated fuel nozzles 114 a-l. The fluid ejected from each ofthe fuel nozzles 114 a-l during the test is collected in one of aplurality of individual measurement vessels 308. The control unit 306periodically samples data from level sensors that are coupled to each ofthe measurement vessels 308, and calculates and displays the flow ratethrough each fuel nozzle 114 a-l throughout the test based on thesampled data. Each of these individual units is discussed in more detailbelow. It is to be appreciated that the test device 300 could beintegrated into a single device, even though it is depicted anddescribed below as three separate units.

Turning now to FIG. 4, a more detailed discussion of a preferredembodiment of the test fluid supply unit 302 will be provided. As shownin schematic form in FIG. 4, the test fluid supply unit 302 houses,within an enclosure 402 (depicted in phantom), various components usedto supply the flow test unit 304 with test fluid. The first of thesevarious components to be discussed is a test fluid supply tank 404. Thetest fluid supply tank 404 stores the test fluid used during the test.Although the test fluid may be any one of numerous fluids, including jetfuel or water, for safety and testing accuracy, the test fluid used isStoddard solvent MIL-PRF-7024 type II. This test fluid is preferablebecause its physical properties at room temperature, e.g. density,viscosity, etc., are similar to that of jet fuel at the temperature atwhich it operates in a turbofan engine. However, the test fluid has amuch higher flash point than jet fuel for improved safety.

A pump 406 takes a suction from the test fluid supply tank 404 anddischarges the test fluid to a fluid manifold assembly 408. Variouscomponents and piping systems are coupled in fluid communication withthe manifold assembly 408. These components include an accumulator 410that helps minimize fluid pressure oscillations within the remainder ofthe system piping. An accumulator dump valve 412 is coupled to the fluidmanifold assembly 408 as well. The accumulator dump valve 412 relievesthe pressure in the accumulator 410 and dumps the fluid back to the testfluid supply tank 404 when the test machine 300 is no longer being used.A safety pressure relief valve 411 is also coupled to the fluid manifoldassembly 408, and is used to relieve fluid pressure in the fluid supplysystem piping back to the test fluid supply tank 404 should the fluidpressure exceed a predetermined pressure setpoint. Finally, a main testfluid supply line 414 is also coupled to the fluid manifold assembly408. This main test fluid supply line 414 directs the test fluiddischarged from the pump 406 to the remainder of the system.

A plurality of additional test fluid flow lines is coupled to the maintest fluid supply line 414 via individual isolation valves. Theseadditional flow lines include a primary supply line 416, a secondarysupply line 418, and a jet-pump bleed line 425. As will be discussed inmore detail further below, the primary supply line 416, which is coupledto the main test fluid supply line 414 by a primary line isolation valve413, directs test fluid to the primary fluid conduits 206 of themanifold sub-assemblies 202, 204 under test. Similarly, the secondarysupply line 418, which is coupled to the main test fluid supply line 414by a secondary line isolation valve 415, directs test fluid to thesecondary fluid conduits 208 of the manifold assembly 200 under test.The primary supply line 416 and secondary supply line 418 each include acoarse and a fine throttle valve coupled in parallel with one another.Specifically, the primary supply line 416 includes a coarse primarythrottle valve 417 and a parallel-connected fine primary throttle valve419. Similarly, the secondary supply line 418 includes a coarsesecondary throttle valve 421 and a parallel-connected fine secondarythrottle valve 423. The primary 417, 419 and secondary 421, 423 throttlevalves are used to adjust the test fluid supply pressure magnitude inthe primary supply line 416 and secondary supply line 418, respectively,during the test. It is to be appreciated that one or more of the primary417, 419 and secondary 421, 423 throttle valves may be eitherelectrically-operated or manually-operated valves. In a preferredembodiment, however, one or more of these valves 417, 419, 421, 423 areelectrically-operated and are automatically positioned by controlsignals supplied from the control unit 306. A pump bypass flow line 422returns pump bypass fluid to the test fluid supply tank 404, through awater cooled heat exchanger 424. It is to be further appreciated thatthe throttle valves may be physically located in either the test fluidsupply unit 302 or in the flow test unit 304. For convenience the valvesare depicted in FIG. 4 with the test fluid supply unit; however, in apreferred embodiment these valves are mounted in the flow test unit 304.

A flow sensor 426 is preferably coupled to the main test fluid supplyline 414. The flow sensor 426 supplies an electrical signalrepresentative of total test fluid flow being supplied by the pump 406,and may be any one of numerous flow sensors including, but not limitedto, a turbine flow meter, a venturi flow sensor, a thermal flow sensor,or a Coriolis-type flow sensor. As will be discussed further below, thetest fluid flow signal is periodically sampled by the test control unit306 and used to display the total test fluid flow rate in the main testfluid supply line 414. A temperature sensor 427 is placed downstream ofthe flow sensor 426, and supplies an electrical signal representative oftest fluid temperature for sample and display by the control unit 306.The temperature sensor 427 may any one of numerous temperature sensorsknown in the art including, but not limited to, a thermocouple or aresistance temperature detector (RTD). A filter 428 may also be includedin the main test fluid supply line 414 to capture any debris that mayget into the test fluid supply tank 404. A first 430, a second 432, anda third 434 pressure sensor are coupled to the main test fluid supplyline 414, the primary supply line 416, and the secondary supply line418, respectively, via individual isolation valves 436. These pressuresensors each supply electrical signals representative of the fluidpressure within the respective supply lines, and may be any one ofnumerous pressure sensors including, but not limited to, bellowssensors, semiconductor sensors, and quartz sensors. As with the testfluid flow signal, the pressure signals supplied by the first 430,second 432, and third 434 pressure sensors are periodically sampled bythe test control unit 306 and used to display the test fluid pressuresin the main 414, primary 416, and secondary 418 supply lines,respectively.

Finally, a return line 437 is in fluid communication with the test fluidsupply tank 404 and, as will be discussed in more detail further below,returns the test fluid supplied to the flow test unit 304 back to thetest fluid supply tank 404 aided by a jet-pump 424 driven by highpressure fluid in a bleed-line 425 that taps into line 414 (upstream ofthe flow meter). A level sensor 438, which may be any one of numerouslevel sensors known in the art including, but not limited to, afloat-type sensor, an optical sensor, or an ultrasonic sensor, suppliesan electrical signal representative of at least a minimum test fluidlevel in the test fluid supply tank 404. As will be discussed furtherbelow, the output of the level sensor 438, and its concomitantcircuitry, provides an indication on the control unit 306 that a minimumlevel of test fluid is in the test fluid supply tank 404.

With reference to FIG. 5, a discussion of the flow test unit 304 willnow be provided. The flow test unit 304, which is depicted in simplifiedschematic form in FIG. 5, includes a primary supply line 502, asecondary supply line 504, a vent line 506, a return line 508, and theplurality of individual measurement vessels 308. The primary supply line502 and the secondary supply line 504 are coupled in fluid communicationwith the primary supply line 416 and the secondary supply line 418,respectively, in the test fluid supply unit 302. Similarly, the returnline 508 is coupled in fluid communication with the return line 437 inthe test fluid supply unit 302. The vent line 506 is coupled to the topsof each of the individual measurement vessels 308 and vents them toatmospheric pressure so that there is no pressure build-up within themeasurement vessels 308, which would adversely affect testing accuracy.

Before proceeding with the description of the remainder of the flow testunit 304, a detailed description of an embodiment of one of themeasurement vessels 308 will first be provided. In doing so, referenceshould be made to FIG. 6, which depicts a cross section side view of asingle measurement vessel taken along line 6—6 of FIG. 3. For the sakeof clarity, FIG. 6 does not depict any external components coupled tothe illustrated measurement vessel 308, except for a level transducer.As FIG. 6 illustrates, the measurement vessels 308 comprise an assemblyof various components, which includes a substantially transparent tube612 coupled between a nozzle mounting plate 614 and a stabilizingmounting plate 616. The tube 612 is substantially transparent so that anoperator can view the spray pattern of the test fluid emitted from thenozzle portion 117 of each of the installed fuel injector nozzle 114a-l. The nozzle mounting plate 614 includes a nozzle assembly mountingclamp 618, and at least two openings. A first opening 620 is configuredto receive the nozzle portion 117 of one of the fuel injector nozzles114 a-l, and a second opening 622 is an air vent. When a manifoldsub-assembly 202, 204 is being tested, the manifold's fuel injectornozzles 114 a-l are mounted on top of the nozzle mounting plate 614,such that the nozzle portions 117 extend through the first opening 620.The nozzle assembly clamp 618 is then used to firmly hold the fuelinjector nozzle 114 a-l in place throughout the test. Though notdepicted, the second opening 622 is coupled to the vent line 506. Thestabilizing mounting plate 616 stabilizes the tube 612 and the othercomponents of the measurement vessel 308, which will now be discussed inmore detail.

A fluid communication tube 624 is coupled between a manifold block 626and the stabilizing mounting plate 616. The fluid communication tube 624receives the test fluid ejected into the tube 612 from the nozzleportion 117 of the installed fuel injector nozzle 114 a-l, andcommunicates it to a fluid distribution path 628 within the manifoldblock 626. The fluid distribution path 628 provides fluid communicationbetween the fluid communication tube 614 and a measuring tube 630. Themanifold block 626 also includes a drain opening 632 in fluidcommunication with the fluid distribution path 628. As will be discussedfurther below, the drain opening 632 is coupled, via a valve, to thereturn line 508.

Similar to the fluid communication tube 624, the fluid measuring tube630 is coupled between the manifold block 626 and the stabilizingmounting plate 616. An opening 634 is provided in an end portion of thefluid measuring tube 630, to vent air displaced by the test fluid thatenters the fluid measuring tube 630. Thus, when test fluid is sprayedfrom the installed fuel injector nozzle 114 a-l into the transparenttube 612, the test fluid drains into the fluid communication tube 624.The test fluid in the fluid communication tube 624 then flows into andthrough the fluid distribution path 628 in the manifold block 626. Sincethe fluid measuring tube 630 is in fluid communication with the fluidcommunication tube 624, fluid level in the fluid measuring tube 630 willrise concomitant with the fluid level in the fluid communication tube624.

A fluid level sensor 636 is mounted to the manifold block 626 and isused to generate electrical signals representative of test fluid levelin the fluid measuring tube 630. The fluid level sensor 636 includes atransceiver 638 coupled to a tube 640 that extends longitudinally withinthe fluid measuring tube 630, from a bottom portion 631 to a top portion633 of the measuring tube 630. The skilled artisan will appreciate thatthe tube 640 need not extend all the way to the top portion 633 of themeasuring tube 630. Nonetheless, to provide the tube 640 with lateralstability, it is so configured in the depicted embodiment. A magneticfloat 642 surrounds the tube 640 and is free to move along thelongitudinal axis of the tube 640, and is buoyant in the test fluid.Thus, as fluid level rises in the fluid measuring tube 630, the magneticfloat will concomitantly rise. It is to be appreciated that the magneticfloat 642 may be an integral piece that is itself magnetized, or may becomprised of separate pieces that provide a magnetic field.

The fluid level sensor 636 operates on the principle oftime-domain-reflectometry (TDR). Under this principle, the transceiver638 periodically transmits electrical pulses into a conductor 641 (shownin phantom) mounted longitudinally within the tube 640. Each of theelectrical pulses traverses the conductor 641 until it reaches themagnetic float 642. Upon attaining the same position as the magneticfloat 642, the electrical pulse is reflected back toward the transceiver638, due to the pulse's interaction with the magnetic field emitted bythe magnetic float 642. The transceiver 638 receives the reflected pulseand determines the distance to the magnetic float 642 based on the timeit took for the transmitted electrical pulse to be reflected back to thetransceiver 638. An example of one such level sensor is sold by BALLUFF,Inc.®, having a Part No. BTL2-P1-0400-Z-EEXA-KL.

It is to be appreciated that the fluid level sensor 636 is not limitedto the embodiment depicted in FIG. 6 and described above. Rather, thislevel sensor is only exemplary of a preferred embodiment due to itsaccuracy and sensitivity. Other types of level sensors known in the artincluding, but not limited to, resistive sensors and optical sensors,may also be used. It is to be further appreciated that the measurementvessels 308 are not limited to the particular depicted configuration.Indeed, the measurement vessels 308 could be configured as single tubes,rather than as an assembly of various components.

Returning once again to FIG. 5, the discussion of the flow test unit 304will now be completed. It was previously mentioned that each of themanifold blocks 626 that form a part of the preferred measurementvessels 308 include a drain opening 632 coupled in fluid communication,via valves 510, with the return line 508. Although these valves 510 maybe any one of numerous valves known in the art, such as manual valves,solenoid operated valves, or hydraulically operated valves, in thedepicted embodiment the valves 510 are air operated valves. In aparticular preferred embodiment, the valves 510 are so-called “pinchvalves,” sold by Red Valve Company, Inc.®, under part number 2600-3/4BUNA N.

To accommodate the preferred drain valve embodiment discussedimmediately above, an air supply line 512 is provided to operate each ofthe valves 510. A solenoid operated, valve 514 is coupled in the airsupply line 512 between each of the valves 510 and a non-illustratedsource of 30 psig air. The test control unit 306 controls the positionof the valve 514. When the solenoid is energized, the valve 514 supplies30 psig air to each of the valves 510 causing each to close,.Conversely, when the solenoid is de-energized, the valve 514 vents thevalves 510 to atmosphere, thus opening them, and causing the measurementvessels 308 to drain the collected test fluid back to the test fluidsupply tank 404.

The control unit 306 is coupled to the various instrumentation andcontrol devices described above and, with reference to FIGS. 7-10, willnow be discussed in detail. Turning first to FIG. 7, the overallarrangement of the control unit 306 will first be described. The controlunit 306 houses within an enclosure 700 various devices that are used tomonitor and control the overall operation of the test machine 300. Thesedevices include a computer 702 (shown in phantom), which may be any oneof numerous general-purpose computers, such as a personal computer (PC),or a specially designed computational device. A display device 704 iscoupled to the computer 702 and displays a test-related user interface,which is discussed in more detail below. A printer, though notexplicitly depicted, is also coupled to the computer 702 and is used toprint out test results. Two input devices are also coupled to thecomputer 702. These input devices include a keyboard 706 and a “mouse”708. It will be appreciated that both of the input devices 706, 708 arenot necessary, and that the control unit 306 would be operable if onlythe keyboard 706 were used. The keyboard 706 allows an operator to inputcertain alpha-numeric data into the computer 702 and, if necessary, tomanipulate a screen cursor to control operation of the computer 702should the mouse 708 not be installed or be inoperative. The mouse 708is used to conveniently position the screen cursor to desired positionson the screen of the display 704 to more easily accommodate computeroperations. Finally, various electrical and electronic components 710are also housed within the control unit enclosure 700. These electricaland electronic components 710 provide an interface between thepreviously described instrumentation and control devices and thecomputer 702, and will now be discussed in more detail.

The various instrumentation and control devices, it will be recalled,include the flow sensor 426, first 430, second 432, and third 434pressure sensors, the fluid supply tank level sensor 438, thetemperature sensor 427, the level sensors 636, the pump 406, theaccumulator dump valve 412, the electrically-operated primary 417 andsecondary 419 throttle valves, and the valve 514. It will be appreciatedthat the flow sensor 426, first 430, second 432, and third 434 pressuresensors, the temperature sensor 438, and the level sensors 636 are eachcoupled to the computer 702 using substantially identical circuitry.Hence, for the sake of brevity, the circuitry associated with only oneof these sensors will be depicted and described in detail. In doing so,attention should now be turned to FIG. 8, which depicts a block diagramof the circuitry 800 associated with each of the level sensors 636.

The level sensor 636 is coupled, via a plurality of safety barriers 802,to an instrumentation interface circuit 804 and a power supply 806. Thesafety barriers 802 are known protection devices that operate on thezener diode principle. That is, the devices limit the voltage potentialacross, and thus the current flow through, the device to which each iscoupled. Thus, the likelihood of any potentially unsafe condition thatcould be caused by an over-voltage or over-current condition to theconnected device is substantially reduced. The instrumentation interfacecircuit 804 receives operational power from the power supply 806 andconverts the signal from the level sensor 636 to an appropriate input tothe computer, which may be either an analog current level (e.g., 4-20milliamperes) or a digital value. The power supply 806 also suppliesoperational power to the level sensor 636. It is noted that the powersupply 806 may supply power to more than one sensor.

The instrumentation interface circuit 804 is coupled to an input/output(I/O) circuit 808, which in turn is coupled to a microprocessor 810within the computer 702. The I/O circuit 808 may be an individual I/Ocircuit dedicated to a single level sensor 636, or a multi-channel I/Ocircuit shared by several sensors. The microprocessor 810 is controlledby software located in a memory 812. The memory 812 may either beintegral to the microprocessor 810 or, as depicted, physically separate.The software, among other things, controls the microprocessor 810 toperiodically sample the signals transmitted from the level sensor 636to, and through, the instrumentation interface circuit 804 and I/Ocircuit 808. The sampling frequency may be any one of numerous samplingfrequencies, but in a preferred embodiment the sampling frequency is atleast five times per second.

The circuitry used to process the control signal to the pump 406, theelectrically-operated primary 417 and secondary 419 throttle valves, andthe valve 514, and which is depicted in FIGS. 9 and 10, is similar tothat described immediately above. However, as FIG. 9 depicts, thecircuitry 900 associated with the pump 406, and the valve 514, includesa relay circuit 902, rather than an instrumentation interface circuit804, and does not include the safety barriers 802, since all of theleads associated with this circuitry remain within explosion-proofcases. The relay circuit 902 is used to control the position of one ormore relay contacts 904, which in turn selectively controls the supplyof power from a power supply 906 to the device being controlled. Thepower supply 906 depicted in FIG. 9 may be a low voltage power supplysimilar to that depicted in FIG. 8, or may be the main power supply tothe test machine 300.

The circuitry 1000 associated with each of the electrically-operatedprimary 417 and secondary 419 throttle valves, one of which is depictedin FIG. 10, differs from that of FIG. 8 in that it includes a drivercircuit 1002 rather than an instrumentation interface circuit 804. Thedriver circuit 1002, under control of the microprocessor 810, suppliespower to the electrically-operated throttle valve 417 (419) to maintainan appropriate test fluid pressure magnitude in the primary (orsecondary) supply line 416 (418), as sensed by the first (second)pressure sensor 432 (434).

As was noted above, the display device 704 is coupled to the computer702 and displays information processed within the computer 702. Inaddition, a printer 818 is preferably coupled to the computer 702 and isused to print out test data processed within the computer 702. Withreference now to FIG. 11, the various types of information displayed andprinted by the display device 704 and printer will be discussed. It willbe appreciated that the fuel manifold test application software run bythe computer 702 is started by, for example, double clicking on an iconon a start-up screen (not illustrated). When this is done, the userinterface screen display 1100 illustrated in FIG. 11 is visible on thedisplay device 704.

The user interface screen display 1100 includes various display fields,some of which are modifiable by an operator via the keyboard 706 and/ormouse 708, and others of which provide for only the display of data.Specifically, the user interface screen display 1100 includes a P/Nfield 1102, a S/N field 1104, a Technician field 1106, and an R/O No.field 1108. The P/N field 1102 allows an operator to enter the specificpart number of the manifold assemblies being tested. The S/N field 1104allows an operator to enter the specific serial number of the manifoldassemblies being tested. The Technician field 1106 allows an operator toenter his/her name, and the R/O No. field 1108 allows an operator toenter the Repair Order number (for accounting/tracking purposes). Belowthese interactive fields are a Date display field 1110 and a CalibrationDue display field 1112. The Date display field 910 displays the currentdate, and the Calibration Due display field 1112 displays the date thatthe next calibration is due for the test machine 300.

Seven so-called “button bars” are displayed below the above-mentionedfields. These seven button bars include a START button 1114, a CONTINUEbutton 1116, a STOP button 1118, a PRINT button 1120, a CALIBRATE button1122, a TECHNICIAN LIST button 1124, and a CREATE RECIPE button 1126. Aswill be described more fully below, operating the START button 1114causes the computer 702 to commence a test sequence, operating theCONTINUE button 1116 causes the computer 702 to continue on to anothertest in the test sequence, and operating the STOP button 1118 causes thecomputer 702 to discontinue a test or test sequence. Operating the PRINTbutton 1120, as it connotes, causes the computer 702 to deliver testresult data to the printer 814 for printing. Operating the CALIBRATEbutton 1122 causes the computer 702 to run a password protectedcalibration procedure, which steps the operator through the calibrationprocess for the test machine 300. The TECHNICIAN LIST button 1124, whenoperated, causes the computer 702 to run a password protected dialogprocedure which allows the operator to edit a database that stores thenames of technicians that are authorized to run the test machine 300. Inorder to run a test with the test machine 300, the name entered in theTechnician field 1106 must match a name in the authorized user database.Finally, operating the CREATE RECIPE button 1126 causes the computer 702to run a password protected dialog procedure which allows the operatorto edit existing, or create new, “test recipes” stored in a test recipedatabase in memory 812. The test recipe database is a part of the fuelmanifold test application software and includes all of the requiredpressure setpoints and flow tolerances that must be met during each ofthe tests. The test recipe database includes an entry associated withevery valid part number that is entered by the operator. Thus, when thepart number is entered in the P/N field 1102, the software automaticallyretrieves the appropriate test recipe from the database. If there are noentries in the recipe database that are associated with the entered partnumber, then a message is displayed on the user interface display screen900.

A Supply Pressure field 1128 displays, in psig (pounds-per-square-inchgauge) the pressure sensed by the first pressure sensor 426. A PrimarySet Pressure 1130 field displays the pressure sensed in the primary line416 in psig by the second pressure sensor 432, and a Secondary SetPressure field 1132 displays the pressure sensed in the secondary supplyline 418 in psig by the third 434 pressure sensorA Fluid Flow field 1134displays the fluid flow sensed by the flow sensor 426 in pph(pounds-per-hour). And, a Fluid Temp field 1136 displays the fluidtemperature sensed by the temperature sensor 427 in degrees Fahrenheit.

Positioned below the above-described pressure, flow, and temperaturedisplay fields are a Pump On/Off button 1138 and a Reservoir OK field1140. The Pump On/Off button 1138, when operated, turns the pump 406 inthe test fluid supply unit 302 on and off. The Reservoir OK field 1140indicates that the fluid level in the test fluid supply tank 404 isabove a minimum required level, as sensed by level sensor 438.Additionally, positioned below the PRINT button 1120 and CALIBRATEbutton 1122 are a Primary Pressure field 1142 and a Secondary Pressurefield 1144 which display the target pressures. These values are providedby the test recipe that is associated with the part number entered inthe P.N field 1102. The largest field in the user interface screendisplay 1100 is the nozzle test data field 1146. Included in this fieldare a Test-Type field 1148, a nozzle Flow Rate field 1150, a numericLevel field 1152, an Initial field 1154, a Difference field 1156, and agraphic Level field 1158. The Test-Type field 1148 displays the type offlow test that is being (or will be) conducted. Thus, as will becomemore apparent further below, the Test-Type field 1148 will displayeither “Primary,” “Secondary,” or “Combined,” to indicate that a primaryflow test, a secondary flow test, or a combined flow test, respectively,is being conducted. Each of the remaining fields in the nozzle test datafield 1146 provides a separate data display for each of the measurementvessels 308 and individual nozzles 114 a-l in the manifold assembly 200being tested. Hence, the nozzle test data field 1146 includes one columnfor each measurement vessel 308 and fuel nozzle 114 a-l in the manifoldsub-assemblies 202, 204. In a preferred embodiment, in which themanifolds consist of twelve nozzles, there are twelve columns in thenozzle test data field. Thus, the nozzle Flow Rate field 1150 displaysthe flowrate (in pph) through each of the nozzles 114 a-l. The numericLevel field 1152 displays the current test fluid volume (in mL) in eachof the measurement vessels 308. The Initial field 1154 displays theinitial test fluid volume (in mL) in each of the measurement vessels 308at the start of a particular flow test. The Difference field 1156displays the difference between the current test fluid volume and theinitial test fluid volume (in mL). And, the graphic Level field 1158graphically displays the current test fluid volume (in mL) in each ofthe measurement vessels 308.

A test result field 1160 is provided on the user interface displayscreen display 1100. The test result field 1160 includes a tolerancefield 1162 that displays the maximum acceptable percentage difference inflow rates through each of the nozzles being tested (% Diff_(max)) thatcomes from the recipe. Above this field is a result field 1164 thatdisplays the calculated maximum percentage difference between nozzleflow rates based on the data gathered during the particular flow test.In particular, the software preferably calculates the maximum percentagedifference between nozzle flow rates (% Diff_(calc)) by subtracting thelowest calculated individual nozzle flow rate from the highestcalculated individual nozzle flow rate, and dividing the difference bythe calculated median flow rate through all of the individual nozzles.It is to be appreciated that this calculation is only exemplary of apreferred method and that other methods of determining % Diff_(calc)could be employed.

Finally, there are three indicators positioned between the nozzle testdata field 1146 and the START button 1114, CONTINUE button 1116, andSTOP button 1118. These indicators are a Check Nozzle indicator 1166, aPress a Button indicator 1168, and a PASS/FAIL indicator 1170. The CheckNozzle indicator 1166 prompts the operator to visually check the spraypattern of each nozzle. The Press a Button indicator 1168 alerts theoperator that the software has completed the current test and is waitingfor the operator to select the next step. The PASS/FAIL indicator 1170illuminates with the appropriate message, either PASS or FAIL, uponcompletion of each test in the test sequence.

The test machine 300 is used to conduct three separate tests on the fuelmanifold assembly 200. As was briefly mentioned above, these testsinclude a primary flow test, a secondary flow test, and a combined flowtest. During the primary flow test, test fluid is directed to only theprimary 212 inlet ports of each manifold sub-assembly 202, 204. Duringthe secondary flow test, test fluid is directed to only the secondary216 inlet ports of each manifold assembly 202, 204. And finally, testfuel flow is simultaneously directed to both the primary 212 andsecondary 216 inlet ports during the combined flow test. It is notedthat these tests are preferably conducted in the described order (e.g.,primary, secondary, combined), but that the present invention is notlimited to this order.

Briefly, the fuel manifold assembly 200 is tested by installing eachsub-assembly 202, 204 in the flow test unit 304, such that the nozzles114 a-l extend through the first openings 620 in each of the measurementvessels 308. This is accomplished by mounting the manifoldsub-assemblies 202, 204 and nozzles 114 a-l on top of each of the nozzlemounting plates 614, and positioning each of the nozzle assemblystabilizers 618 to firmly hold the injector nozzles 114 a-l in place.The primary 502 and secondary 504 supply lines are then coupled to theprimary 212 and secondary 216 inlet ports of the end fuel nozzles 114 a.Then, with the fuel manifold test application software running, theoperator enters the appropriate data, starts the pump 406, and pressesthe START button 1114 to initiate the primary flow test. When theprimary flow test is completed, the computer 702 calculates and displaysthe maximum percentage difference (% Diff_(calc)) between nozzle flowrates, and provides the appropriate message in the PASS/FAIL indicator1170. The operator then presses the CONTINUE button 1116 to initiate thesecondary flow test. After the secondary flow test is complete, thecomputer 702 once again calculates and displays the maximum percentagedifference (% Diff_(calc)) between nozzle flow rates, and provides theappropriate message in the PASS/FAIL indicator 1170. Thereafter, theoperator once again presses the CONTINUE button 1116 to initiate thecombined flow test. And once again, upon completion of the test thecomputer 702 calculates and displays the maximum percentage difference(% Diff_(calc)) between nozzle flow rates, and provides the appropriatemessage in the PASS/FAIL indicator 1170. It is noted that during each ofthe primary, secondary, and combined flow tests, the operator observesthe spray pattern of the test fluid emitted from each of the nozzles 114a-l. This is possible because of the measurement vessels' substantiallytransparent tube 612. It is additionally noted that upon completion ofthe combined flow test, the test data can be printed out by pressing thePRINT button 1120, and the test machine 300 is ready to begin anothertest cycle.

Having described the test machine 300 hardware in detail, and havingvery generally described how the software components control the testmachine 300 to carry out the primary, secondary, and combined flowtests, a more detailed description of the flow test methodology carriedout by the software loaded onto computer 702 will be provided. In thisregard, the parenthetical references to “STEPs” in the followingdiscussion correspond to the particular reference numerals of theprocess flowchart depicted in FIG. 12.

The discussion of the process depicted in FIG. 12 is predicated on thefact that a fuel nozzle has been installed in the flow test unit 304, asdescribed above. After the operator properly installs the fuel nozzleassembly 200, he/she then enters the appropriate part number, serialnumber, and his/her name in the appropriate fields, and turns the pump406 on by pressing the Pump On/Off button 1138.

When the operator presses the START button 1114, the process 1200carried out by the software begins (STEP 1202). At this point, thesoftware checks the P/N field 1102, S/N field 1104, Technician field11106, and R/O No. field 1108 for valid data (STEP 1204). If theinformation entered in these fields is invalid, a message is displayedon the user interface screen 1100 to alert the operator (STEP 1206). If,on the other hand, the information is valid, the process proceeds to thenext step.

In the next step, the computer 702 retrieves the appropriate test recipefrom the test recipe database (STEP 1208). It will be recalled that thetest recipe database includes a test recipe for each valid part numberentered in the P/N field 1102. After the test recipe is loaded, thecomputer 702 positions the valve 514 so that the drain valves 510 moveto the shut position (STEP 1210). The appropriate isolation valve 413(415) is opened, and the appropriate throttle valves 417, 419 (421, 423)are then opened and adjusted until the pressure in the primary(secondary) supply line 416 (418) reaches the required magnitude, assensed by the first (second) pressure sensor 432 (434) (STEP 1212). Atthis point, test fluid is flowing through each of the nozzles 114 a-land is being collected in each of the measurement vessels 308. It willbe appreciated that in an alternative embodiment, in which the throttlevalves 417, 419 are manually-operated, these valves will be adjustedbefore the START button 1114 is pressed.

In any case, after the drain valves 510 are shut and the supply pressureis adjusted, the computer begins sampling the level signals from each ofthe level sensors 636. Using the sampled level signals, the computer 702calculates and displays the test fluid volume collected in each ofmeasurement vessels 308 both numerically (in the numeric Level field1152) and graphically (in the graphic Level field 1158) (STEP 1214). Thecomputer 702 monitors each of the measurement vessel levels anddetermines if all of the level sensors 636 indicate a change inmeasurement vessel level after a first predetermined time period (STEP1216). If not all of the level sensors 636 indicate a change, it is anindication of a potential fault, either mechanical or electrical innature. As a result the test is discontinued, the drain valves 514 areopened, and an appropriate message is displayed on the user interfacescreen 1200 (STEP 1218).

If all of the level sensors 636 indicate a level change, the test fluidflow into the measurement vessels 308 continues, and then when each ofthe measurement vessels 308 has collected a first predetermined volumeof test fluid, as set in the test recipe, the test fluid volume in eachof the measurement vessels 308 at that point in time is displayed in theInitial field 1154, and the nozzle flow test portion begins. The testfluid continues to flow through the fuel nozzles 114 a-l and into themeasurement vessels 308 until one of two events occur. These events areeither a second or “final” predetermined test fluid volume is collectedin each measurement vessel 308 (STEP 1220), or a second predeterminedtime period has passed since each measurement vessel 308 collected thefirst predetermined test fluid volume (STEP 1222). If the secondpredetermined time period has passed and the second predetermined testfluid volume has not been collected, this is indicative of a potentialfault as well. As a result, the test is discontinued, the drain valvesare open, and an appropriate message is displayed on the user interfacescreen 1200 (STEP 1224).

Once each of the measurement vessels 308 collects the secondpredetermined volume of test fluid before the second predetermined timeperiod has elapsed, the computer 702 in the control unit 306 stopssampling the signals from each of the level sensors 636 (STEP 1226) andcalculates and displays the maximum flow rate variation (% Diff_(calc))between each of the fuel nozzles 114 a-l in the result field 1164 (STEP1230). In a preferred embodiment, if the calculated maximum flow ratevariation is within the value indicated in the tolerance field 1162,then the result field 1164 is highlighted in green (STEP 1232) and thePASS/FAIL indicator 1170 displays PASS. Conversely, if the maximumcalculated flow rate variation exceeds the value in the tolerance field1162, then the result field 1164 is highlighted in red (STEP 1038) andthe PASS/FAIL indicator 1170 displays FAIL. It is to be appreciated thatother methods of indicating a failed test could also be used, such asdifferent colors, the sounding of an alarm, or a separate messagealtogether. In any case, the data from the test is then stored in memory(STEP 1236), and the drain valves are opened (STEP 1238).

After the primary flow test, the operator can stop the testing bypressing the STOP button 1118 (STEP 1240), or proceed to the next testby clicking on the CONTINUE button 1116 (STEP 1242). Should the operatorclick on the CONTINUE button 1116, the computer 702 in the control unit306 would initiate the secondary flow test, since the previous test wasa primary flow test (STEPS 1244-1246). The secondary flow test isconducted similar to the primary flow test except that the primary shutoff valve 413 is shut and the secondary shut off valve 415 is opened;and the secondary throttle valves 421, 423 are adjusted to the pressurein the test recipe (STEPS 1210-1238). Thus, test fluid flows only intothe secondary inlet ports 216.

Upon completion of the secondary flow test, the operator may once againstop the testing by pressing the STOP button 1118 (STEP 1240), orproceed to the next test by clicking on the CONTINUE button 1116 (STEP1242). This time, if the operator clicking on the CONTINUE button 1116,the computer 702 initiates the combined flow test, since the previoustest was a secondary flow test (STEPS 1248-1250). The combined flow testis conducted similar to the primary and secondary flow tests except thatboth the primary 413 and secondary 415 shut off valves are open, and allof the throttle valves 417, 419, 421, 423 are adjusted to the pressurein the test recipe (STEPS 1210-1238). Thus, test fluid flows into boththe primary 212 and secondary 216 inlet ports.

Once the combined flow test is completed the test sequence ends (STEP1252). At this point, the operator can shut the test machine 300 down orreplace the manifold assembly 200 just tested with another manifoldassembly 200. Although not illustrated in the process flowchart 1200,the operator may also print out the test results from the completed testsequence. A non-limiting example of the content and format of one suchprintout 1300 is depicted in FIG. 13.

The test machine 300, including both its hardware and softwarecomponents, provide significant features and advantages over other fuelmanifold test devices. Most notably, it provides increased accuracy andrepeatability over other devices and methods. It provides real-timelevel sensing and display throughout the test, which other devices andmethods do not provide. Operators can view the fuel nozzle spraypatterns throughout the flow test sequence. Additionally, the testdevice is configured as a closed loop system.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt to a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to any particular embodiment disclosedfor carrying out this invention, but that the invention includes allembodiments falling within the scope of the appended claims.

We claim:
 1. A computer-readable medium storage medium containingcomputer executable code for instructing a computer, which is coupled toa test stand that is configured to test fluid flow distribution througha turbine engine fuel manifold and one or more fuel nozzles, and thatincludes a plurality of fluid measurement vessels each operable toreceive a test fluid discharged from one of the fuel nozzles, to performthe steps of: periodically determining and displaying a volume of testfluid discharged from each of the fuel nozzles until each of themeasurement vessels have collected a predetermined volume of the testfluid; and periodically calculating and displaying test fluid flow ratethrough each of the fuel nozzles based on the periodically determinedtest fluid discharge volume.